# NTSB CEN15LA131: Bell-Watson 47 G, N43762, North Little Rock, AR, January 29, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: January 29, 2015, 17:00 local (23:00 UTC) - Place: North Little Rock, AR - Coordinates: 34.83472, -92.258613 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.8347&lon=-92.2586&mi=10 - Phase of flight: [Emergency descent](https://openairdocs.org/ntsb-phases/600) (OpenAirDocs' grouping) - Defining event: [Autorotation: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report February 3, 2016 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Little Rock FSDO - NTSB case key (mKey): 90670 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN15LA131 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/90670/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=90670 - Page: https://openairdocs.org/ntsb/CEN15LA131 ## Probable cause The flight instructor’s failure to maintain adequate rotor rpm during the practice touchdown autorotation, which resulted in a subsequent loss of helicopter control and impact with terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Rotorcraft flight control: main rotor control](https://openairdocs.org/ntsb-findings/01046710): Aircraft › Aircraft propeller/rotor · Incorrect use/operation (probable cause); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-findings/01046710/cases.md?model=1181077), [All aircraft, 28 cases](https://openairdocs.org/ntsb-findings/01046710/cases.md) - [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=1181077), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md) - [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Instructor/check pilot (probable cause); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-findings/02063015/cases.md?model=1181077), [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1181077), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Autorotation: Miscellaneous/other](https://openairdocs.org/ntsb-events/900) (defining event); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-events/900/sequence.md?model=1181077), [All aircraft, 1,556 cases](https://openairdocs.org/ntsb-events/900/sequence.md) - [Autorotation: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-events/060/sequence.md?model=1181077), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Autorotation: Loss of control in flight](https://openairdocs.org/ntsb-events/240); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-events/240/sequence.md?model=1181077), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) - [Landing-flare/touchdown: Abnormal runway contact](https://openairdocs.org/ntsb-events/090); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-events/090/sequence.md?model=1181077), [All aircraft, 1,506 cases](https://openairdocs.org/ntsb-events/090/sequence.md) - [Landing-flare/touchdown: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-events/096/sequence.md?model=1181077), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) - [Post-impact: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338); cases with it: [Bell-Watson 47-G, 1 case](https://openairdocs.org/ntsb-events/338/sequence.md?model=1181077), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis The flight instructor reported that he was demonstrating a power-off touchdown autorotation to a large, open paved ramp area. He added that, while flaring the helicopter for touchdown, the rotor "seemed to run have out of energy" but that the rotor tachometer indications did not indicate a reduction in rotor rpm. The tail skid subsequently contacted the asphalt, and the helicopter bounced into a nose-low attitude. The main rotor blades then struck the pavement and the tailboom, which resulted in the complete separation of the tail rotor assembly, the partial separation of both main rotor blades, and damage to the skid gear. The helicopter rotated right about 180 degrees from the landing direction and came to rest upright. A postaccident examination of the helicopter, including the dual tachometer indicator and the rotor tachometer indicator, found no preaccident anomalies that would have precluded normal operation. The accident sequence is consistent with an inadvertent loss of rotor rpm and subsequent loss of helicopter control. ## Factual narrative On January 29, 2015, about 1700 central standard time, a Bell/Watson 47-G helicopter, N43762, was substantially damaged after impacting terrain during landing at North Little Rock Municipal Airport (ORK), North Little Rock, Arkansas. The flight instructor and student pilot were not injured. The helicopter was registered to Shamu Aviation; North Little Rock, Arkansas; and was operated by a private individual. Day visual meteorological conditions (VMC) prevailed at the time of the accident and a flight plan had not been filed for the 14 Code of Federal Regulations Part 91 local instructional flight. According to the flight instructor, he was manipulating the controls and the student pilot was "following along" as the flight instructor was demonstrating a power off touch-down autorotation to a large open paved ramp area. While flaring for touchdown the flight instructor allowed the rotor RPM to get too low, the tail skid made contact with the asphalt and the helicopter bounced into a nose low attitude, then "fell through" and had a hard landing. During the accident sequence the main rotor blades struck the pavement and the tail boom which resulted in the complete separation of the tail rotor assembly, the partial separation of both main rotor blades, and hard landing damage to the skid gear. The helicopter rotated to the right about 180 degrees from the landing direction and came to rest upright. The flight instructor shut down the operating engine, and both occupants exited without assistance. The flight instructor reported that the rotor "seemed to have run out of energy" but the rotor tachometer indications did not indicate a reduction in rotor RPM. After the accident, the dual tachometer indicator and the rotor tach generator were removed from the helicopter and examined at a Federal Aviation Administration approved repair station. The examinations showed that the rotor tachometer indicator was operating nominally, but was slightly out of calibration. The pointer for the engine tachometer indicator was free floating and evidence showed it had recently detached from its main shaft hairspring. The generator output for the four-pole rotor tach generator was also nominal. Examination showed that it matched specified calibration data at 50 rotor RPM and at 300 rotor RPM, and the phasing and frequency was correct, but the voltage output was slightly low. Except for the broken engine tachometer indicator pointer no preaccident anomalies were found which would have precluded normal operation. Clinton National Airport (LIT), Little Rock, Arkansas, was located about 7 miles at 171 degrees from the accident site, at an elevation of 257 feet msl. At 1653 the surface weather observation site at LIT reported wind from 340 degrees at 15 knots with gusts to 20 knots, visibility of 10 miles, few clouds at 3,500 feet, scattered clouds at 15,000 feet, broken clouds at 25,000 feet, temperature 11 degrees Celsius (C), and dew point 1 degree C, with an altimetersetting of 30.31 inches of Mercury. ## Aircraft - Registration: [N43762](https://openairdocs.org/deregistered/N43762-2017-07-24), registration cancelled 2017-07-24, S/N W1007, built 1992 (OpenAirDocs) - Reported make and model: BELL-WATSON 47 G - Registry model: [Bell-Watson 47-G](https://openairdocs.org/model/bell-watson-47-g) (registry code 1181077) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Helicopter - Serial number: W1007 - Year built: 1992 - Airframe hours: 260 - Engines: FRANKLIN O-335-5D 200 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Continuous airworthiness, January 10, 2015, 14 hours before - Departed: ORK, North Little Rock, AR - Destination: ORK, North Little Rock, AR - Airport: ORK, North Little Rock Muni, runway 35, 3,019 × 75 ft, asphalt - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 45; injuries: none; airline transport, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane, helicopter; medical: class 2, without waivers/limitations; last flight review April 15, 2014; seat: left; restraint: lap only; flight hours: 7,500 total, 250 in this make and model, 65 in the last 90 days, 25 in the last 30 days, 3 in the last 24 hours - Student pilot; age 21; injuries: none; student; medical: class 1, without waivers/limitations; seat: right; restraint: lap only; flight hours: 9 total, 4 in this make and model, 9 in the last 90 days, 13 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 340° at 15 knots, gusting 20 - Visibility: 10 statute miles - Lowest ceiling: 25,000 ft broken - Temperature: 52 °F, dew point 34 °F - Altimeter: 30.30 inHg - Observed at: KLIT, 7 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20150129002439A](https://openairdocs.org/incident/20150129002439A), Jan 29, 2015: Bell-Watson 47-G, North Little Ro, AR, Substantial damage. At approximately 1700 CST on 1/29/2015, Bell/Watson 47G experienced a hard landing during flight instruction while practicing autorotations. The instructor and… ## Docket (7 files) The files NTSB released with the investigation on December 21, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=90670. 3.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435126&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Map (item 2, .PDF, 84 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435127&FileExtension=.PDF&FileName=Map-Master.PDF - IIC's Estimate of Flight Instructor's Flight Experience (item 3, .PDF, 52 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435128&FileExtension=.PDF&FileName=IIC%27s%20Estimate%20of%20Flight%20Instructor%27s%20Flight%20Experience-Master.PDF - IIC's Summary of Findings (item 4, .PDF, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435129&FileExtension=.PDF&FileName=IIC%27s%20Summary%20of%20Findings-Master.PDF - Examination Report - Rotor Tach System Components (item 5, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435130&FileExtension=.PDF&FileName=Examination%20Report%20-%20Rotor%20Tach%20System%20Components-Master.PDF - Weather Summary (item 6, .PDF, 109 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435131&FileExtension=.PDF&FileName=Weather%20Summary-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 7, .PDF, 189 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435132&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.